Sea’s

• How waves erode


  1. Hydraulic action: The power of water as it crashes against the coast

  2. Abrasion: Waves pick up stones and throw them against the coast. These stones abrade the coast

  3. Compressed air: Air in rocks becomes trapped by the incoming waves. The trapped air puts pressure on the rocks. When the water retreats (moves out), the air expands and the pressure drops. This repeated compression and release causes the rock to shatter

  4. Attrition: Stones carried by the waves hit off each other. Over time they are worn down and smoothed

  5. Solution: Certain rocks, such as limestone are dissolved by the water
• Waves- Waves are formed from wind moving across the surface of the sea. The

  strength of the wind and the length of sea that it passes over (the fetch)

  affects the size of the waves.
• Headlands and bays - 1 Bavs and headlands are formed on coastlines where an area of soft rock is eroded more auicklv than the hard

  rock in the headland. This is known as differential erosion

  2 Soft rock, such as sandstone, is more easily eroded and begins to form a hollow in the coast known as a bay.

  3 The area of hard rock, such as granite, is left jutting out on either side into the sea. This is called the headland.

  Examples include Dublin Bay, Howth Head, Co. Dublin, and Liscannor Bay, Co. Clare.
• Sand dunes - Sand dunes are mounds of sand that build up on the shore beyond the

  high-tide mark at the back of the beach
• Sand dunes - Sand on the beach is dried by the wind.

  2 Dry sand is lighter; so, the wind can then blow

  3 The sand becomes trapped by vegetation or

  other barriers.

  • Marram grass

  4 It then builds up to form sand dunes.

  5 Marram grass is sometimes planted on sand

  dunes to stop the sand blowing further inland.

  Marram grass has deep roots and is a thick,

  coarse grass that is resistant to salt
• Groynes - are concrete or wooden walls or fences that

  are built out into the sea at right angles to the coast.

  They work to reduce longshore drift by trapping

  the sediment carried by waves. They trap the sand,

  which then builds up the level of the beach.

  An example can be seen at Rosslare, Co. Wexford.
• Sea walls are built to break the power of the

  incoming waves. They are curved at the top to push

  the waves back out to sea.

  An example can be seen at Bray, Co. Wicklow.
• Gabions -are steel wire cages filled with stones. They

  are then stacked on top of each other where they

  act like a sea wall. They are used to slow down or

  prevent erosion by breaking the power of the waves.

  An example can be seen at Lahinch, Co. Clare.
• Rock Armour/Large

  Boulders-

  Large boulders known as rock armour are

  placed at the base of a cliff, sand dune or

  sea wall. When a wave breaks, it will hit the

  rock armour and lose its energy. This reduces

  erosion of the coastline.

  An example can be seen at Strandhill, Co. Sligo.
• Sea Case Study: North Bull Island, Co. Dublin
• and Tourism along

  Ireland's Coast

  -Tourism - Settlement